[2.2.x] Fixed #30312 -- Relaxed admin check from django.contrib.sessions to SessionMiddleware subclasses.

Backport of efeceba589974b95b35b2e25df86498c96315518 from master

2 files changed, 8 insertions, 2 deletions

diff --git a/docs/ref/checks.txt b/docs/ref/checks.txt
index 9d48138076..a4267131ed 100644
--- a/docs/ref/checks.txt
+++ b/docs/ref/checks.txt
@@ -657,13 +657,13 @@ The following checks are performed on the default
   :setting:`INSTALLED_APPS` in order to use the admin application.
 * **admin.E406**: :mod:`django.contrib.messages` must be in
   :setting:`INSTALLED_APPS` in order to use the admin application.
-* **admin.E407**: :mod:`django.contrib.sessions` must be in
-  :setting:`INSTALLED_APPS` in order to use the admin application.
 * **admin.E408**:
   :class:`django.contrib.auth.middleware.AuthenticationMiddleware` must be in
   :setting:`MIDDLEWARE` in order to use the admin application.
 * **admin.E409**: :class:`django.contrib.messages.middleware.MessageMiddleware`
   must be in :setting:`MIDDLEWARE` in order to use the admin application.
+* **admin.E410**: :class:`django.contrib.sessions.middleware.SessionMiddleware`
+  must be in :setting:`MIDDLEWARE` in order to use the admin application.
 
 ``auth``
 --------
diff --git a/docs/releases/2.2.1.txt b/docs/releases/2.2.1.txt
index 0ca76bcbf8..b7b1f6112d 100644
--- a/docs/releases/2.2.1.txt
+++ b/docs/releases/2.2.1.txt
@@ -49,3 +49,9 @@ Bugfixes
 
 * Fixed a regression in Django 2.2 that caused an exception to be raised when
   a custom error handler could not be imported (:ticket:`30318`).
+
+* Relaxed the system check added in Django 2.2 for the admin app's dependencies
+  to reallow use of
+  :class:`~django.contrib.sessions.middleware.SessionMiddleware` subclasses,
+  rather than requiring :mod:`django.contrib.sessions` to be in
+  :setting:`INSTALLED_APPS` (:ticket:`30312`).